linux-kernel - Re: [PATCH] leds: sun50i-a100: avoid division-by-zero warning

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Message-Id: <42f522b5-6406-4bef-8180-3a431ee884a5@app.fastmail.com>
Date:   Wed, 13 Dec 2023 07:32:14 +0100
From:   "Arnd Bergmann" <arnd@...db.de>
To:     guoren <guoren@...nel.org>, "Arnd Bergmann" <arnd@...nel.org>
Cc:     "Pavel Machek" <pavel@....cz>, "Lee Jones" <lee@...nel.org>,
        "Chen-Yu Tsai" <wens@...e.org>,
        "Jernej Skrabec" <jernej.skrabec@...il.com>,
        "Samuel Holland" <samuel@...lland.org>,
        "Nathan Chancellor" <nathan@...nel.org>,
        "Palmer Dabbelt" <palmer@...osinc.com>,
        "Nick Desaulniers" <ndesaulniers@...gle.com>,
        "Bill Wendling" <morbo@...gle.com>,
        "Justin Stitt" <justinstitt@...gle.com>,
        linux-leds@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: Re: [PATCH] leds: sun50i-a100: avoid division-by-zero warning

On Wed, Dec 13, 2023, at 02:26, Guo Ren wrote:
> On Wed, Dec 13, 2023 at 5:45 AM Arnd Bergmann <arnd@...nel.org> wrote:
>>  {
>>         const struct sun50i_a100_ledc_timing *timing = &priv->timing;
>>         unsigned long mod_freq = clk_get_rate(priv->mod_clk);
>> -       u32 cycle_ns = NSEC_PER_SEC / mod_freq;
>> +       u32 cycle_ns;
>>         u32 control;
>>
>> +       if (!mod_freq)
>> +               return;
>> +
> Shall we need err_disable_bus_clk?
>
> + static int sun50i_a100_ledc_set_timing(struct sun50i_a100_ledc *priv)
> - static void sun50i_a100_ledc_set_timing(struct sun50i_a100_ledc *priv)

I'm not worried about it too much, as there is already an error check
on priv->mod_clk being unavailable during initialization. The case that
the warning is about is just for build-testing on architectures that
don't even use COMMON_CLK.

     Arnd